import {
    JSONParse as json_parse,
    JSONStringify as json_stringify,
} from "https://unpkg.com/json-with-bigint@3.4.4/json-with-bigint.js";

/// PKCE key generation.
export const PKCE = {
    /// Create a verifier for [`PKCE::challenge`].
    verifier: async (length) => {
        let text = "";
        const possible =
            "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";

        for (let i = 0; i < length; i++) {
            text += possible.charAt(
                Math.floor(Math.random() * possible.length),
            );
        }

        return text;
    },
    /// Create the challenge needed to request a user token.
    challenge: async (verifier) => {
        const data = new TextEncoder().encode(verifier);
        const digest = await window.crypto.subtle.digest("SHA-256", data);
        return btoa(
            String.fromCharCode.apply(null, [...new Uint8Array(digest)]),
        )
            .replace(/\+/g, "-")
            .replace(/\//g, "_")
            .replace(/=+$/, "");
    },
};

export default function tetratto({
    host = "https://tetratto.com",
    api_key = null,
    app_id = 0n,
    user_token = null,
    user_verifier = null,
    user_id = 0n,
}) {
    const GRANT_URL = `${host}/auth/connections_link/app/${app_id}`;

    function api_promise(res) {
        return new Promise((resolve, reject) => {
            if (res.ok) {
                resolve(res.payload);
            } else {
                reject(res.message);
            }
        });
    }

    // app data
    async function app() {
        if (!api_key) {
            throw Error("No API key provided.");
        }

        return api_promise(
            json_parse(
                await (
                    await fetch(`${host}/api/v1/app_data/app`, {
                        method: "GET",
                        headers: {
                            "Atto-Secret-Key": api_key,
                        },
                    })
                ).text(),
            ),
        );
    }

    async function query(body) {
        if (!api_key) {
            throw Error("No API key provided.");
        }

        return api_promise(
            json_parse(
                await (
                    await fetch(`${host}/api/v1/app_data/query`, {
                        method: "POST",
                        headers: {
                            "Content-Type": "application/json",
                            "Atto-Secret-Key": api_key,
                        },
                        body: json_stringify(body),
                    })
                ).text(),
            ),
        );
    }

    async function insert(key, value) {
        if (!api_key) {
            throw Error("No API key provided.");
        }

        return api_promise(
            json_parse(
                await (
                    await fetch(`${host}/api/v1/app_data`, {
                        method: "POST",
                        headers: {
                            "Content-Type": "application/json",
                            "Atto-Secret-Key": api_key,
                        },
                        body: json_stringify({
                            key,
                            value,
                        }),
                    })
                ).text(),
            ),
        );
    }

    async function remove(id) {
        if (!api_key) {
            throw Error("No API key provided.");
        }

        return api_promise(
            json_parse(
                await (
                    await fetch(`${host}/api/v1/app_data/${id}`, {
                        method: "DELETE",
                        headers: {
                            "Atto-Secret-Key": api_key,
                        },
                    })
                ).text(),
            ),
        );
    }

    async function remove_query(body) {
        if (!api_key) {
            throw Error("No API key provided.");
        }

        return api_promise(
            json_parse(
                await (
                    await fetch(`${host}/api/v1/app_data/query`, {
                        method: "DELETE",
                        headers: {
                            "Content-Type": "application/json",
                            "Atto-Secret-Key": api_key,
                        },
                        body: json_stringify(body),
                    })
                ).text(),
            ),
        );
    }

    // user connection
    /// Extract the verifier, token, and user ID from the URL.
    function extract_verifier_token_uid() {
        const search = new URLSearchParams(window.location.search);
        return [
            search.get("verifier"),
            search.get("token"),
            BigInt(search.get("uid")),
        ];
    }

    /// Accept a connection grant and store it in localStorage.
    function localstorage_accept_connection() {
        const [verifier, token, uid] = extract_verifier_token_uid();
        window.localStorage.setItem("atto:grant.verifier", verifier);
        window.localStorage.setItem("atto:grant.token", token);
        window.localStorage.setItem("atto:grant.user_id", uid);
    }

    async function refresh_token(verifier) {
        if (!user_token) {
            throw Error("No user token provided.");
        }

        return api_promise(
            json_parse(
                await (
                    await fetch(
                        `${host}/api/v1/auth/user/${user_id}/grants/${app_id}/refresh`,
                        {
                            method,
                            headers: {
                                "Content-Type": "application/json",
                                "X-Cookie": `__Secure-atto-token=${user_token}`,
                            },
                            body: json_stringify({
                                verifier,
                            }),
                        },
                    )
                ).text(),
            ),
        );
    }

    async function request({
        api_path,
        method = "POST",
        content_type = "application/json",
        body = "{}",
    }) {
        if (!user_token) {
            throw Error("No user token provided.");
        }

        return api_promise(
            json_parse(
                await (
                    await fetch(`${host}/api/v1/${api_path}`, {
                        method,
                        headers: {
                            "Content-Type": content_type,
                            "X-Cookie": `__Secure-atto-token=${user_token}`,
                        },
                        body:
                            content_type === "application/json"
                                ? json_stringify(body)
                                : body,
                    })
                ).text(),
            ),
        );
    }

    // ...
    return {
        // app data
        app,
        query,
        insert,
        remove,
        remove_query,
        // user connection
        GRANT_URL,
        extract_verifier_token_uid,
        refresh_token,
        localstorage_accept_connection,
        request,
    };
}

export function from_localstorage({
    host = "https://tetratto.com",
    app_id = 0n,
}) {
    const user_verifier = window.localStorage.getItem("atto:grant.verifier");
    const user_token = window.localStorage.getItem("atto:grant.token");
    const user_id = window.localStorage.getItem("atto:grant.user_id");

    return tetratto({
        host,
        app_id,
        user_verifier,
        user_id,
        user_token,
    });
}